Apparatus for subsurface surveying



Oct, 19, 1937. D. G. HAw'rHoRN APPARATUS FOR SUBSURFACE SURVEYING 2Sheets-Sheet 1 INVENTOR xga/w13 MM ATTORNEYS ///////////////////,V/l//f/Filed Jan. 14. 1936 WIT Oct. 19, 1937. D. s. HAwTHoRN APPARATUS FORSUBSURFACE SURVEYING Filed Jan. 14, 1936 2 Sheets-Sheet 2 Ww III/ATTORNEYS INVENTOR www Patented Oct. 19, 1937. i

APPARATUS FOB SUBSURFACE SURVEYING David G. Hawthorn, Tulsa, Okla.,miglior to Geophysical Research Corporation,

N ew K York,

N. Y., a corporation of New Jersey Application January 14, 193B,Serial'No. 59,096

3Claims.

This inventionrelates. to apparatus for subsurface surveying.

In a recently developed method of exploring sub-surface formations, thedrill bit of a standard boring machine is used as an electrode forpassing electricity into the earth at the bottom of a bore hole in orderto test the electrical resistance of the formation in which the bit isoperating to determine the nature of such formation. An object of thisinvention isa drill stem incorporating an insulated conductor designedto carry electricity to the drill bit.

A drill stem embodying the invention consists as usual of a number oflengths of pipe joined end to end by the usual male and femaleconnecters at the ends of the lengths of pipe. In each connecter is aninsulated electrical contact which is adapted to be engaged by a contactin a connecter of the opposite type upon union oi said connecters. Asmall conduit is fixed to the inner periphery of the pipe and through itpasses an insulated electrical conductor having its ends connected tosaid contacts. A drill collar which is electrically insulated internallyand externally, is interposed between the bottom connecter of the drillstem and the drill bit thus allowing the bit to function as an electrodeand is provided with an electrical contact to engage the electricalAcontact in said bottom connecter. With this arrangement, the connectingtogether of the several lengths of pipe in the usual mannerautomatically builds up an insulated electrical path from the top of thedrill stem to the drill bit. The normal procedure in increasing thelength of the drill stem as the depth of the bore increases or inremoving the drill stem for replacement of .the bit is in no wayinterfered with by the arrangement for conducting electricity to thedrill bit.

Other objects, novel features and advantages of this invention willbecome apparent from the following speciiication and accompanyingdrawings, wherein:

Fig. 1 is a diagrammatic view of a drill stem embodying the invention;

Fig. 2 is an elevation of one section of the drill stem connected ateither end to other sections;

Fig. 3 is a longitudinal section through the bit and collar by which itis connected tothe drill stem; s l

Fig. 4 is a longitudinal view of a male and female connecter in positionto be coupled;

Fig. 5 is a similar view with the connecters coupled;

Iv l i wf (Cl. Z55-28) Fig. 6 is a transverse section on the line 6-6 ofFig. 5;

Fig. 7 is an enlarged fragmentary view of the contacts in the male andfemale connecters in posltion'about to be engaged;

Fig. 8 is a view similar to Fig. 'i with the contacts in engagement, and

Fig. 9 is an elevation of the female connecter contact.

As shown in Fig. l, the drill stem consists of a series of pipe lengthsliljointed together by couplers or tool joints II with a drill collar I2attached to the bottom length and being in turn attached to the drillbit I3. Each coupler II consists of a maleV connecter I4 and a femaleccnnecter I5 which are permanently secured to the pipe lengths Ill andwhich are provided with cooperating tapered screw-threaded portions byengagement of which the two connecters are joined to form a coupler II,such coupler construction being ofthe standard type now in general useand known as a tool joint.

In the bore of the male connecter is provided a contact I6 and in thebore of the female connecter is provided a contact I'I. The contact I6comprises a metal ring enclosed with insulation such as rubber exceptalong its upper edge. The insulation covered contact is mounted in asplit sleeve I8 which rests against a shoulder in the connecter bore andhas a force fit in said b'ore. The contact I'I consists of a metal helixterminating at each end in an annulus, the contact being completelyenclosed with insulation such as rubber except along its bottom edge.The upper end of the insulation covered contact I'I is mounted in asplit sleeve I9 which bears against 'a shoulder in the connecter boreand has a force t therein. 'I'he insulation on the connecter I6 extendsbeyond the uncovered edge of the contact to form an annular channel.'I'he insulation on the contact I'I tapers at the lower edge thereof toform a wedge which is received in the channel at the upper edge of thecontact I 6. The taper of the walls of the channel is less than thetaper of the wedge so that the walls of the channel are sprad uponengagement of the wedge in the channel to insure eective insulation ofthe contacts I6 and I'I along the meeting edges thereof. A conduit 2l)extends longitudinally of each length of pipe l0 and is brazed orotherwise connected permanently to the inner periphery of the pipeI Aninsulated electrical conductor 25 extends through the conduit 20 and iselectrically connected at one end to contact I6 and at the opposite endto a contact I1. The space between the conductor 2| and the inner wallof the conduit 20 may be lied with any suitable plastic material to holdthe conductor rmly in place.

The drill bit Il is' of standard construction and is provided with ascrew-threaded boss 22 which projects into the screw-threaded box at thelower end of the drill collar I2. 'I'he bore of the drill collar isprovided with a liner `23 of insulating material and is surrounded by asleeve 24 of insulating material such, for example, as bakellte. Theupper end of the sleeve 2l is screw-threaded and extends into thescrew-threaded box of a connecter Ila which is provided with a contactI6 from which an insulated conductor Ila leads to the upper end of thedrill collar l2. A ring 2l of insulating material is interposed betweenthe upper end of the drill collar I2 and a shoulder in the bore of theconnecter Ila. The surface of the drill collar is roughened in anysuitable manner, such as knurling, to prevent slippage of the sleeve 2lon the drill collar.

In a drill stem made in accordance with the invention, the usual mixtureof mud and water is forced through the central bore and out thedischarge ducts I3a in the bit in the -usual manner, the cylindricalshape of the contacts I6 and i1 and their supporting members permittingfree flow of such liquid. The top length of pipev I is connected in theusual manner to the standard Kelly joint 2l which is associated in theusual manner with a rotating drive wheel 29. The Kelly joint 2l isprovided with a suitable electrical contact (not shown) which engagesthe top connecter Ii and is. connected by any suitable collector ringand brush arrangement with the positive terminal of a battery B throughan ammeter or ohm meter M, the negative terminal of the battery beinggrounded. Electrical energy. is thus supplied to thedrill blt and themajor part of the electrical current is discharged from the bit into thesub-surface formation at the bit blade as the best contact is at thispoint. I'he bit thus acts as a disspatingY electrode and from readingsobserved on the ammeter or ohm meter, variations in the resistance ofthe' sub-surface formation may be determined, thereby giving indicationof the character of the formation.

As the bore increases in depth, additional sections may be added to thedrill stem in the usual manner merely by disconnecting the Kelly jointfrom the top length of pipe, inserting the addi-v tional section andconnecting the Kelly joint to the top end of the added section. Thedrill stem may be drawn up and disconnected in the usual manner for thepurpose of replacing the bit and without any precaution having to betaken with respectto the electrical connections.

In joining together the male and female connecters at the ends of twosections ofy pipe, it is necessary only to project the male section intothe female section until the threads engage and then effect slightrelative rotation thereof to couple the connecters firmly together.`'I'he exposed edges of the contacts i6 and I1 will be brought intoengagement at about the'same time that the threads of the connectersengage each other and in the final coupling together of the connectersthe edges will be in sliding contact as the connecters are rotated intotight coupling engagement. The contact I'l is sulciently resilient to beslightly compressed during the coupling operation while exertingsumcient pressure to insure good electrical conductive engagementbetween the edges of the contacts. The overall insulation of thecontacts prevents any leakage of electrical energy, thus insuring ahighly conductive electrical path from the top to the bottom of thedrill stem. a

I claim:

1. A drill stem section comprising a length of pipe, a conduit fixed tothe inner periphery thereof, male and female threaded connecters atopposite vends of said pipe, a metal annulus rigidly supported in oneconnecter, a metallic helical member supported in the other connecterand terminating in a second annulus, said first annulus and saidhelicalmember being coated with electrical insulation except for an edge ofeach annulus, the annulus of each connecter being effective to beengaged by an annulus in a connecter of the opposite type upon union ofsaid connecters,` and an insulated electrical conductor passing throughsaid conduit and having its ends connected to said contacts.

2. A drill stem section according to claim 1 in which the insulation forone annulus extends beyond the exposed edge thereof to form a taperedtrough. and the insulation for the other annulus tapers to the exposededge thereof to form a wedge.

3. A drill stern section according to claim 1 in which the insulationfor one annulus extends beyond the exposed edge thereof to form atapered trough and the insulation forthe other annulus tapers to theexposed edge thereof to form a wedge, the taper of the trough beingdifferent than the taper of the wedge.

DAVID G. IIAWTHORN.

